• Steel and Composite Structures
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• v.5 no.1
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• pp.49-70
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• 2005

This paper reports on finite element analysis techniques that may be applied to the study of circular hollow structural sections and related bearing connection geometries. Specifically, a connection detail involving curved steel saddle bearings and a Structural Tee (ST) connected directly to a large-diameter Hollow Structural Section (HSS) truss chord, near its open end, is considered. The modeling is carried out using experimentally verified techniques. It is determined that the primary mechanism of failure involves a flexural collapse of the HSS chord through plastification of the chord wall into a well-defined yield line mechanism; a limit state for which a shell-based finite element model is well-suited to capture. It is also found that classical metal plasticity material models may be somewhat limited in their applicability to steels in fabricated tubular members.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.149-152
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• 1999

This paper addresses major issues in localising sound sources in space using the experimental data set of head-related responses in the time or frequency domain. They come from the technical realisation steps for implementing the convolution of HRIR's with sound sources, the cross-talk cancellation for transaural filtering, the matched time delay compensation, etc. in real, those technical matters seem to be minor because they can be realised in off-line signal processing schemes. This paper puts much emphasis on what we misunderstood about the sets of HRTF's or HRIR's, More specifcaily, the sets of HRTF's or HRIR's of course supply relevant information to sound localisation but include much useless 'rubbish' that have made for us to fail to put spatial image into real souno signals such as voices and music's. This paper proposes possible reasons for such failure and, furthermore, introduces detained subjects that should be challenged so as to resolve them.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.767-775
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• 2005

Power Supply System for electric railways is diversified with technical development and is required high technologies. especially, recently there is required many research and development for earthing to ensure safety of people and protection of installations. Generally, leakage resistance is high between rail and ground at tunnel section of subway. because of short circuit of feeding line, earthing interference by transient overvoltage between signals and communication system, and insulation failure, it can damage to human and equipments To minimize these obstacles, earthing equipment is installed at underground section of railway, but it brings about problems in accordance with operate each earthing system to be not enough required protection provisions for electrified railways. This paper proposes effective earthing method to be concerned about installation cost and maintenance. The validity of the proposed earth method is verified by simulation results at underground section of railways.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1398-1402
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• 2007

In a high speed train, OBCS(On-Board Computer System) is a up-to-date computer control system that provide controlling, monitoring, maintaining and reparing of the important device, supporting a driver, status of a train, service maintenance, managing the remote control mode, driving order & control, control of a electrical or pneumatic circuit and a passenger service. In general, OBCS is located in each car but in a power car, both main and auxiliary computers are used. These avoid a network collision and maintain the independence of condition and failure records with the information of line number, train number and car number. This paper is intended to provide the information about the identification coding method of domestic and foreign OBCS, for the new high speed train (KTX-II).

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.224-225
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• 2000

Transparent and hard materials such as sapphire are used for many industrial applications as optical windows, hard materials on mechanical contact against abrasion, and substrate materials for opto-electronic semiconductor devices such as blue LED and blue LD etc. The materials should be cut along the proper shapes possible to be used for each application. In case of blue LED, the blue LED wafer should be cut to thousands of blue LED pieces at the final stage of the manufacturing process. The process of cutting the wafer is usually divided into two steps. The wafer is scribed along the proper shapes in the first step. It is inserted between transparent flexible sheets for easy handling. And then, it is broken and split in the next step. Harder materials such as diamonds are usually used to scribe the wafer, while it has a problem of low depth of scribing and abrasion of the harder material itself. The low depth of scribing can induce failure in breaking the wafer along the scribed line. It was also known that the expensive diamond tip should be replaced frequently for the abrasion. (omitted)

• Journal of Korean Society for Quality Management
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• v.16 no.1
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• pp.59-66
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• 1988

On-line QC by Taguchi has two approaches of: the cost-oriented (cost-emphasis) QC and the process-oriented (quality-emphasis) QC. The main concern of this paper is to estabilish and recommend a desirable one as a QC target. Simulation is employed to solve the question, and the failure cost (A), appraisal cost (B), and prevention cost (C) are adopted as decision variables. In conclusion, the process-oriented QC is the recommendable approach as far as there is no remarkable cost difference between the two approaches and possible to apply on.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.132-137
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• 2012

To enhance the CAE accuracy, the definition of material behavior is one of key influence on the result. In case of plastic material with fiber reinforcement, the anisotropic material behavior should be taken into account to increase of CAE accuracy. BASF has developed an innovative CAE tool, ULTRASIM$^R$, which is capable of generating material models of thermoplastic materials for structural simulation. ULTRASIM$^R$, not only the glass fiber orientation effect, but also the weld line effect, tensile-compression anisotropy, strain rate effect are combined in a non-linear material law, which will be evaluated in a unique failure criterion, thus resulting in an highly accurate CAE approach.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.4
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• pp.71-83
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• 1989

The optimization in the machining process has been a long-standing goal of the manufacturing community. The optimization is composed of two main subjects;one is to select an optimum cutting condition, and the other is to detect the emergency situation and take necessary actions in real-time base. This paper proposes a reliable and practical guide system whose purpose is the optimization of cutting conditions, and the detection of tool failure in the machining process. The optimal cutting conditions are determined through the estimation of tool wear rate and the establishment of access- ible field from the measured cutting temperature and force. Tool breakage is detected by the normal force component acting on minor flank face extracted from on-line sensed feed force and radial force. In experiments, the proposed guide system has proved availability for the decision of reliable cutting conditions for the given tool-work system and the detection of tool breakage in ordinary cutting environments.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.31-36
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• 1997

Various methods of finite element modeling for welded part are examined and the stamping simulation of automotive body is presented by using the explicit finite element code PAM-STAMPTM. The process of stamping simulation is suggested step by step, and then the gravity, binder wrap, forming, trimming and springback of front door inner are analyzed. It shows good agreements with real product in the aspects of deformed shape and failure area. The door inner with laser-tailor welded blank is simulated, in which deformed shape, movement of welde line and formability are predicted.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.456-458
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• 1995

This paper describes a diagnosis of power transformers by on-line detection of ultrasonic signals. Partial discharge in power transformer generates ultrasonic signals. The trend of the ultrasonic signal number can be measured when partial discharge is generated in HV Winding. The trend of the ultrasonic signal number could easily be distinguished by taking moving average. The insulation failure due to partial discharge in transformers can be predicted based in the trend analysis of the number of ultrasonic signals caused by partial discharge.